Coupling-dependent rates of energy transfers from photoexcited Mott insulators to lattice vibrations

TL;DR

This study investigates how different electron-lattice couplings affect the rate of energy transfer from photoexcited Mott insulators to lattice vibrations, revealing the importance of symmetry and coupling strength in these processes.

Contribution

It provides a detailed analysis of energy transfer pathways in correlated electron systems with various electron-lattice couplings using exact quantum and classical simulations.

Findings

Energy transfer to lattice vibrations depends on symmetry-breaking of electron states.

Couplings modulating Coulomb repulsion transfer energy regardless of symmetry.

Strong electron-lattice couplings can significantly influence energy relaxation pathways.

Abstract

Photoexcited states are relaxed by transferring energy to the environments. In order to study which coupling allows fast energy transfer to lattice vibrations in correlated electron systems, we calculate the time evolutions of the kinetic energies of different types and frequencies of lattice vibrations. The one-dimensional half-filled Hubbard model is augmented with electron-lattice couplings that modulate transfer integrals, site energies, and Coulomb repulsion strengths. The time-dependent Schr\"odinger equation is solved for exact many-electron wave functions, and the classical equation of motion for the lattice displacements. In order to transfer energy to classical lattice vibrations that modulate transfer integrals or site energies, the translational invariance must be broken to give optical activity to an electronic excitation with wave number $ \pi $ and to these lattice vibrations. On the other hand, a certain amount of energy is always transferred to lattice vibrations that modulate Coulomb repulsion strengths, irrespective of the symmetry of the ground state, as long as the corresponding electron-lattice couplings are present. In strongly correlated electron systems, these couplings can be strong, although they are usually insignificant because their effects on the equilibrium properties can be absorbed into redefinition of Coulomb repulsion strengths. We will discuss competition or collaboration between energy transfer pathways through different types of electron-lattice couplings.